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EVALUATION
OF LIGHT AS A NON-PHYSICAL CUE TO GUIDE DOWNSTREAM-MIGRATING LAMPREY
TRANSFORMERS INTO TRAPS
2U.S. Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research
Laboratory, 1 Migratory Way, Turners Falls, MA USA 01376.
3 U.S. Geological
Survey, Great Lakes Science Center, Hammond Bay Biological Station, 11188 Ray
Road, Millersburg, MI USA 49759.
December 2018
ABSTRACT:
Trapping downstream migrating metamorphosed sea lamprey (Petromyzon marinus;
transformers) is a largely unexploited opportunity to limit damage to the
fishery for the sea lamprey control program. Currently, the high cost of trap operation is not justified by the number of
transformers captured. The GLFC and fishery managers have expressed
interest in expending control efforts to this life stage but first tools must
be developed that can allow for maintenance-free fishing. One possible solution
is the use of non-physical cues to direct downstream migrants to traps in
areas where debris and ice fouling are manageable. Here, to determine how speed and direction of juvenile
sea lamprey downstream movement was influenced by exposure to light, recently
metamorphosed downstream migrating sea lamprey (Petromyzon marinus) were exposed to light
cues in several orientations and intensities at night under controlled flowing
water conditions in a laboratory flume. Then, a follow-up study evaluated how
sea lamprey chemosensory alarm cue and combinations of light and alarm cue
influence downstream migration in the same bioassay. When exposed to low intensity white light,
sea lamprey were more likely to be captured in a net closest to the light cue
array compared to a dark control condition, suggesting some attraction to
light. At higher light intensities, sea lamprey progressed downstream at a
slower rate. Reduction in downstream
movement rates in response to higher light intensities may be representative of
a photonegative behavior where juvenile lamprey in strong light (> ~100 lux)
suspend downstream migratory behavior to remain stationary or burrow, possibly
to avoid detection by predators. When exposed to
alarm cue, sea lamprey arrived downstream faster, but did not avoid the alarm
cue plume by moving perpendicular to flow.
When alarm cue and light was applied simultaneously in a push-pull
configuration, alarm cue still triggered enhanced downstream movement (push)
and more sea lamprey were still captured in the net nearest the light (pull),
so more lamprey were captured in the lighted net. These studies show that
juvenile sea lamprey detect and behaviorally respond to light and alarm cues
and these cues may be useful in management when used independently or
integrated. Additional systematic
experiments are needed to understand how responses are
influenced by context and the presentation of the stimulus.